Diaphragm



1,633,950 June 28 1927- A. NYMAN DIAPHRAGM FiledKSept. 20, 1923 V 2Sheets-Sheet 2 /5 I A f 6 l i? 5 HMWW" @www-mma QW 6/ gf 61 5f PatentedJune 28, 1927.

UNITED STATES PATENT.

ALEXAnNER NYMAN, 0F SWSSVLE, PENNSYLVANIA, ASSIGNGR WESW ELECTRIC r.MANUFACTURING CGMPANY, A GORPRTIN 331" .Application le September 2G,i923. Serial No. 653,783,

My invention relates to diaphrairnis, hav ingr particular relation todiaphrajgms desinned for use in loud speaking` telephone de ces. .lt is,however, applicable to other acoustic devices such as micrrn'ihones,phonographs and the like.

In its broadest aspect, an important object of my invention is toprovide a diaphragm whereby sound waves may he faithfully translatedinto correspondingly modulated electrical energy, and vice versa,without impa'iring the quality, tone and quantity of the translatedenergy.

More si'iecifically, another object ot my invention is to provide adiaphragm which is characterized bythe absence of resonant points and hythe fact that the stillness of the diaphragm, in opposite directions7 issuhstantially the same.

A further object of my invention is to provide a diaphragm which issimple in design and construction and which may be readily manufacturedby existing automatic machinery with minimum expenditures oi' time andof money.

The diaphragrns of the prior ari` `for the most part, consist:- of plaincircular discs of soule desired material, as, tor instance, mica, paper.or iron, depending.,r upon the specific application thereof. Experiencehas shown that such diaphragms have one resonance frequency for thediaphragm as a whole, and one or more other partial resonantfrequencies, the latter dependingi upon the relative arrangement of suchkinks or 'avy places as may occur in the surface of the diaphragm.

The foregoing difficulties have been partiallyr overcome in certainprior art diaphragms by impressing upon the diaphragm corrugations inthe form of concentric cil cles. However, iit was found that theconcentrically disposed corrugations gave rise to harmonics, depending,rupon their distance from the center of vibration of the diar phragm.

In practicing my invention, the abovementioned difficulties are avoidedby providing the diaphragm with corrugations, the spacing of which iscontinuously variable with respect to the center of vibration of saiddiaphragm. Thus, points on the diaphragm 0f equal radii, but ofdifferent annular position may give to diii'erentl frequencies whichcomplet. partially balance, all as explained more herein allein lin oneembodiment of my in vi. vide a diaphragm with a plural ot'coneentrically disposed spiral tions so arranged as to provide a, tiallysmooth central portion and at the periphery thereoi, the annuir. centralportion being1 position diate the opposiieiaces ot said i and thecorrupations terminatin, tral portion and in the annulus in tion thatthe. diaphragm has an i ness in opposite directions.

Other objects and applications et' vcntion, as 'ivell as details ofconsti and arrangement, will be apparent iully hereinafter, when takenin with the accompanying description, claims and drawing' wherein,

Figure l is a transverse sectional view of a (lished diaphragm. i Fig. 2is a top plan vien7 of the embodiment of my invention, y

Figs. 3 and 4 are enlarged transverse sectional views ofthe apparatusshown in 2. the sectionalv planes being indicated hy the lines III-IHand IV-ll/T, respectively.

Fig. 5 is a view similar' to Fig. 2 illustrat ing a modification in thearrangement of corrugations, and

Figs. G and 7 are enlarged transverse sectional views taken on the linesVI-VI and VII-VII, respectively, of Fig. 5.

In the preferred embodiment of my invenn tion shown in Fig, 2, adiaphragm l com prising' a circular disc 2 of resilient lmateriai isprovided with a series of spiral corrugations 3 and 4. The eorrugrationsoriginate in an annular portion 5 which denes the periphery of thediaphragm l and terminate in a substantially smooth central portion ilhaving a central point 7, the latter being designed to serve as thecenter of vibration ot' the diaphragm l. The series of corrngations 3and 4 are so pressed into the disc as to position the central portion 6and the annular portion 5 in a plane sulostantial'lj@u midway betweenthe opposite faces thereof.

A characteristic of a pair of spirals, as shown in the drawing, is thatpoints iSd@ preferred Sil i it is noted that diametrically oppositelypo-' cli apart and of equal radii, are on different spirals and ofcorresponding elevations or depressions. For instance, points a and b,shown in Fig. 3, which are spaced 18()O apart and which have equal radiiwith respect to the center of vibration 7 of the diaphragm l, arepositioned, respectively, on the series of spiral corrugations 3 and tand are of corresponding elevation. Similarly,

sitioned points al and b1, shown in Fig. at, which are equally spacedwith respect to the center ot vibration 7, are respectively positionedon the series of corrugations 3- and e and are of correspondingdepression. Thus,

points on the diaphragm 1,Which are equally spaced with respect to thecenter of vibration thereoi2 and which are angularly spaced 180 apart,have corresponding displacements on different series of spirals and,hence, the formation of Aharmonic circular nodal points is avoided.

It is known that when a force is applied to a dished diaphragm, as shownin Fig. l, in a direction indicated by arrow d, the displacement thereofis much greater than when a corresponding force is oppositely applied tothe diaphragm in a direction indicated by arrow e, that is to say, byreason of the curvature of the diaphragm, the stiffportion ness thereof,in opposite directions, is not equal. rIhis principle is applied in myvinvention, wherein it may be noted that, in 'the sectional view shownin Fig. 3 the annuand the central portion 6 are dished in one direction;whereas in Fig. Il, which is a sectional view displaced from that ofFig. 3, the annular portion 5 and the central portion 6 are dished inthe opposite direction. Hence, it follows that the undesirable etlectnoted in Fig. l is entirely absent in the embodiment of my inventionshown in Fig. 2, therebyI roviding a diaphragm which has an equ,stiffness in the tivo directions.

In Fig. 5 is shown a modification which differentiates over theembodiment of my invention shown in Fig. 2 in the provision of a singlespiral groove 8 only, rather than a double spiral groove as previouslyshown. In this modification, points having equal radii andangularlyspaced 180 apart have opposite elevations with respect to acentral portion 6 or an annular portion 5 as shown, for instance, bypoints f, g and f', g', in Figs. (i and 7, respectively. In vieiv of theopposite displacement of equally spaced points i800 apart, harmonics atthese points are avoided.

While I have shown but two embodiments ot my invent-ion, for the-purposeof describing the same and illustrating their principle of operation, itis apparent that various changes and modifications may be made thereinWithout departing from the spirit of my invention. I desire, theretoi-e, that only such limitations shall be imposed thereon as areindicated by the appended claims or as are demanded by the prior art.

I claim as my invention:

l. A diaphragm provided with a plurality of series oi spiralcorrngations, and also ivith a Substantially smooth central portiondisposed intermediate the, opposite surfaces of said diaphragm, saidseries ol corrugations terminating in said central portion.

:2. A reinforced diaphragm, the rcini'orccment being symmetricallyarranged relative to the tivo faces of the diaphragm whereby equaldisplacements in the tivo directions will result from the similarapplication of equal forces tothe tivo faces.

3. A diaphragm provided with a spiral corrugation, the radii of saidspiral at diametrieally opposite points being such that a harmonieestablished at one such point substantially cancels that established atthe other.

4. A diaphragm provided with spiral corrugations, a substantially flatcentral portion and a narrow annulus at the edge of said diaphragm, saidspiral corrugations being so arranged that said diaphragm has an equalstitlness in opposite directions.

5. A diaphragm provided With a plurality' of series of spiralcorrugatigns so disposed as to leave a substantially flatcentralportion, said portion being disposed substantially midway between theopposite tacos ot said diaphragm, said corrugziti'ons terminating insaid central portion in such relative relation that the stitl'ncss ofsaid central portion in opposite directions is equal.

G. A diaphragm provided with a plurality ofseries of concentricallydisposed spiral corrugationsso arranged as to provide a substantiallysmooth central portion and an annulus at the periphery thereof,l saidannulus and said central portion being positioned intermediate theopposite faces of said diaphragm, said series of eorrugations terminaring in said annulus and in said central portion in such relation as toavoid a dished condition of the diaphragm.

7 A diaphragm provided with a plurality of concentric spiralcorrugations, said spirals .being vsuch that points at equal distancesfrom the common center on radii that divide 360 into as many equal partsas there are spirals have corresponding elevations or depressions.

8. A diaphragm provided with a pair of concentrically disposed spiralcorrugations, said spirals being such that points 180 apart and of equalradii have corresponding elevations or depressions.

\l 9. A. diaphragm provided With a plurality of concentric spiralcorrugations so designed that points at equal distances from the commoncenter on radii that divide 360 into twice as many equal parts as thereare spirals have substantially opposite displacements.

10. A rdiaphragm provided with corrugations in the form of a doublespiral. wherein points 180 apart and of equal radii are on differentspirals and of corresponding elevations or depressions. v

11. A diaphragm provided with a plurality of sei-ies of concentricallydisposed spiral cox'rugations, a substantially smooth central portionand an annulus at the periphery, said annulus and said central portionbeing positioned intermediate the opposite faces of said diaphragm,sa'id spirals being of. s design that points 1800 apart and of er radiihave corresponding elevations.

12. A corrugated diaphragm having 1: substantially flat portionv`axiaiiy displaf i portions adjacent said dat porion, the a placementbeing` opposite along diari 91ers ai 2G right angles to each other.

In testimony whereof7 I liaveiieifeunio subscribed my name this Lith daySep tomber, 1923.

ALEXANDER NYMAN.,

